Variable diameter pulley



.Sept 16 1953 R. SEYFARTH 2,851,894

VARIABLE DIMETER PULLEY F110!! July 11, 1955 IN VENTOR.

2,851,894 Patented Sept. 16, 1958 2,851,894 VARIABLE DIAMETER PULLEY Robert Seyfarth, Mason, Mich., ssslgnor to General VMotors Corporation, Detroit, Mich.,

Delaware application July 1r, i955, sensi N'o. 521,218

1 claim. (cnn- 23041) v A Y.

This invention relates to devices in which centrifugal force acting on a body of liquid contained between rotating parts causes axial displacement between the parts, and more particularly to such a device of extremely simple design and having means for containing the liquidV without the use of the usual seals.

While vdevices auch as variable diameter V-belt pulley drives and the like in which liquid under the action of centrifugal force causes axial displacement between the halves of the pulley are known, their use has sometimes been economically prohibitive and otherwise undesirable due to intricate design thereof requiring a number of seals and other elements which are subject to failure.

It is now proposed to provide a device of this kindhaving a minimum number of parts and requiring none of the usual seals since the liquid is contained in a completely enclosed, hollow exible torus disposed between the parts for rotation therewith. -Tll'he device is thus very inexpensive to manufacture and install and substantially foolproof in operation.

In the drawings:

Figure 1 is an axial cross-sectional view of a device embodying the invention in the inoperative position.

Figure 2 is a fragmentarycross-sectional view similar to Figure l and illustrating the device in the operative position.

Figure 3 is an enlarged perspective view partly in crosssection and illustrating a structural element of the invention.

Referring to the drawings in greater detail, Figure l illustrates only one of a number of possible embodiments of the invention, namely a variable diameter V-belt pulley assembly.

The assembly comprises a rotatable drive or driven shaft 12 having secured thereto by any suitable means or formed integrally therewith an annular pulley half 14 characterized by a cylindrical recess 16 aud an annular flange 18 having a tapered face 20. Thus, the pulley half 14 rotates with the shaft l2. Also secured for rotation with the shaft 12 is a second pulley half 22 having a cylindrical body 23 adapted to be received in the cylindricalrecesslandanannulartlangealsohavinga tapered face 25 so that a V-belt 19 may be received between the flanges 18 and 24.

The spline connection 26 between the shaft 12 and the pulley half 22 not only causes these parts to rotate together, but also permits axial movement of pulley half 22 along shaft 12. Any other suitable equivalent connection may be employed in place of the spline connection 26.

A collar 28 is fixed to the shaft on the side of pulley half 22 opposite pulley half 14, the collar having a guide portion 30 and a shoulder 32. It is apparent that an iutegral shoulder would serve equally well in the place of the separate collar.

a corporation of--- toward the pulley half 14 so that the cylindrical 16. with 18 and 24 in engagement, as by Figure l. Here again, any other equivalent spring devioe'eouldh employed in the place of coil spring 34. l

A thinwalled,g; hollow, completely enclosed torus 38 made of exible material such as rubber or the like and Alled with a liquid is positioned inthe recess 16. The

torus 38 preferably has a circular cross-section as shown by Figure 3. although other cross-sectional shapes could A coil spring 34 is positioned on the shaft 12 s'o that 7 its-ends abut against the pulley half 22 around the hub 36 and the shoulder 32. The spring thus urges the pulley cylindrical be employed, The outer diameter-"of the torus 38 is;l preferably greater the diameter of the recess 16 so' that the sorua will-have suicient frictional engagement 'with the assernlalyilll to rotate therewith. Also, the 'crossoectionsl diameter of the torus is greater than the normal axial spacing between pulley halves 14 and 22.

tangular cross section.

When the assembly 10 is caused to rotate at high speeds.theliquidisthrowntotheouter peripheryofthe recess 16 which causes the exible torus 38 to assume an oppositely latteaed shape approaching that shown by Fig- The generally rectangular shape maintained by 38 in position allows the center of the 40 and the container to have a maxim rotationalpathdismeterstslltimes, thusobtaining the maximum eeet from a given quantity of liquid. This naturally forces the pulley half 22 lo the right against spring 34 andseparates the flanges 18 and 24 so'that the V-belt 19 drops lower between the flanges. lt is prefable, however, to provide a spring 34 having sutlicient tension to overcome the natural tendency of the v-belt to spread the pulley halves. The exact cross-sectional shape of the torus 34 depends, of course, onfthe rotational speed of the assembly ll and it varies between the extremes shown by Figures l and 2. At any rate, there is a gradual automntic adiustment of the eifective pulley diameter as the assembly 10 increases or in rotational velocity.

It is to be noted vthat the proposed structure is extremely simple in design and it has been found to be foolproof and elfective in operation, particularly since few moving partsandnosealsofanykindarerequired.

Inanactualtestanaxialforce of llpounds was produced by a one-half inch detlcction at 3200 R. P. M. with a 6-inch diameter torus tlled with plain water. The use of a heavier iluid, such as a calcium chloride solution for example, would give more force.

It is apparent that many variations in the preferred embodiment shown and -described are possible without departing from the scope of the invention. For instance, both of the pulley halves could be provided with shallower recesses and they need not telescope, and both pulley halves could be spring loaded for axial movement in op- The device is adapted for other applications, such as a clutch or s governor, .in which case rattling produced by the usual weights, levers, etc., would be eliminated. Also.. a pair of variable diameter pulleys of the type shown could be employed to provide an automatic change speed mechanism similar to a Reeves drive.

What is claimed is:

A variable diameter pulley assembly comprising, a rotatabledrive shaft having external splines formed thereon, a rst annular pulley half including a cylindrical recess formed by a tint radially extending portion and a rst portion, said llrst radially extending portion is normally positioned within the cylindrical re-.

3 being axially and nonrotatably secured to said shaft for rotation therewith, said first pulley half having an annular 'ange formed on and extending radially outward of said first cylindrical portion',` said ange having a tapered face detiningA one pulley surface, a second annular pulley half formed to include n second radially extending portion and. a second cylindrical portion teleseopically received within said tr'st cylindrical portion radially inward of said tirst pulley half annular flange and having an annular tlange extending radially outward therefrom axially l0 adiaecnt said first pulley half annular angedaid second annularange having a tapered face defining the other pulley surface, saidsccond radially extending portion having internal splines formed th'e'ein and engaging said drive shaft splines. to permitaxial Ybut' not rotating move-` ment of said second pulley half relative to said second pulley half, m'eans -mounted on said shaft for biasing said second radial and cylindrical portions into said cylin- 4 drical portion, and exible sealed duid containing expansible means received between said tirst and second radial portions and within said first cylindrical portion for rotation therewith, said expansible means axially expand, ing against said radial portions under centrifugal force to move said pulley 'halves apart a distance proportional to the spcedof said shaft, thereby varying the working diameter of the pulle um Cmd inline aie funs pausa,

UNITED sTA'ras PATENTS 1.618.644 Dickson Feb. zz, 192i 2,310,081 Hm nb. z: 1943 15 2543.351 NSalisbury Feb. 21, 1951 2,612,055 Miner --..----.A-- sept. so, 195

FOREIGN PA'raNfxs 401.1310 Y om: Britain Mar. 23. 1931 

